Direct export . The programs have been tested over a wide range of the variables X, Y, Z, and ~t. UNBIASED ESTIMATE = 0.8578 FORTRAN STOP $ REFERENCES Bardsley, W. E., 1983, Confidence limits for fission-track dating: Jour. . MU) GO TO 50 R I =X2 +XL R2=X2+XU R3"X3-XL R4=X3 -XU RD=XL-XU IF (~.